RFC 3413 SNMP Applications December 2002
Note that there are no restrictions on which types of applications
may be associated with a particular SNMP engine. For example, a
single SNMP engine may, in fact, be associated with both command
generator and command responder applications.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
1.1. Command Generator Applications
A command generator application initiates SNMP Read-Class and/or
Write-Class requests, and processes responses to requests which it
generated.
1.2. Command Responder Applications
A command responder application receives SNMP Read-Class and/or
Write-Class requests destined for the local system as indicated by
the fact that the contextEngineID in the received request is equal to
that of the local engine through which the request was received. The
command responder application will perform the appropriate protocol
operation, using access control, and will generate a response message
to be sent to the request's originator.
1.3. Notification Originator Applications
A notification originator application conceptually monitors a system
for particular events or conditions, and generates Notification-Class
messages based on these events or conditions. A notification
originator must have a mechanism for determining where to send
messages, and what SNMP version and security parameters to use when
sending messages. A mechanism and MIB module for this purpose is
provided in this document. Note that Notification-Class PDUs
generated by a notification originator may be either Confirmed-Class
or Unconfirmed-Class PDU types.
1.4. Notification Receiver Applications
A notification receiver application listens for notification
messages, and generates response messages when a message containing a
Confirmed-Class PDU is received.
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RFC 3413 SNMP Applications December 20021.5. Proxy Forwarder Applications
A proxy forwarder application forwards SNMP messages. Note that
implementation of a proxy forwarder application is optional. The
sections describing proxy (3.5, 4.3, and 7) may be skipped for
implementations that do not include a proxy forwarder application.
The term "proxy" has historically been used very loosely, with
multiple different meanings. These different meanings include (among
others):
(1) the forwarding of SNMP requests to other SNMP entities without
regard for what managed object types are being accessed; for
example, in order to forward an SNMP request from one transport
domain to another, or to translate SNMP requests of one version
into SNMP requests of another version;
(2) the translation of SNMP requests into operations of some non-SNMP
management protocol; and
(3) support for aggregated managed objects where the value of one
managed object instance depends upon the values of multiple other
(remote) items of management information.
Each of these scenarios can be advantageous; for example, support for
aggregation of management information can significantly reduce the
bandwidth requirements of large-scale management activities.
However, using a single term to cover multiple different scenarios
causes confusion.
To avoid such confusion, this document uses the term "proxy" with a
much more tightly defined meaning. The term "proxy" is used in this
document to refer to a proxy forwarder application which forwards
either SNMP messages without regard for what managed objects are
contained within those messages. This definition is most closely
related to the first definition above. Note, however, that in the
SNMP architecture [RFC3411], a proxy forwarder is actually an
application, and need not be associated with what is traditionally
thought of as an SNMP agent.
Specifically, the distinction between a traditional SNMP agent and a
proxy forwarder application is simple:
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RFC 3413 SNMP Applications December 2002
- a proxy forwarder application forwards SNMP messages to other SNMP
engines according to the context, and irrespective of the specific
managed object types being accessed, and forwards the response to
such previously forwarded messages back to the SNMP engine from
which the original message was received;
- in contrast, the command responder application that is part of what
is traditionally thought of as an SNMP agent, and which processes
SNMP requests according to the (names of the) individual managed
object types and instances being accessed, is NOT a proxy forwarder
application from the perspective of this document.
Thus, when a proxy forwarder application forwards a request or
notification for a particular contextEngineID / contextName pair, not
only is the information on how to forward the request specifically
associated with that context, but the proxy forwarder application has
no need of a detailed definition of a MIB view (since the proxy
forwarder application forwards the request irrespective of the
managed object types).
In contrast, a command responder application must have the detailed
definition of the MIB view, and even if it needs to issue requests to
other entities, via SNMP or otherwise, that need is dependent on the
individual managed object instances being accessed (i.e., not only on
the context).
Note that it is a design goal of a proxy forwarder application to act
as an intermediary between the endpoints of a transaction. In
particular, when forwarding Confirmed Notification-Class messages,
the associated response is forwarded when it is received from the
target to which the Notification-Class message was forwarded, rather
than generating a response immediately when the Notification-Class
message is received.
2. Management Targets
Some types of applications (notification generators and proxy
forwarders in particular) require a mechanism for determining where
and how to send generated messages. This document provides a
mechanism and MIB module for this purpose. The set of information
that describes where and how to send a message is called a
'Management Target', and consists of two kinds of information:
- Destination information, consisting of a transport domain and a
transport address. This is also termed a transport endpoint.
- SNMP parameters, consisting of message processing model, security
model, security level, and security name information.
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RFC 3413 SNMP Applications December 2002
The SNMP-TARGET-MIB module described later in this document contains
one table for each of these types of information. There can be a
many-to-many relationship in the MIB between these two types of
information. That is, there may be multiple transport endpoints
associated with a particular set of SNMP parameters, or a particular
transport endpoint may be associated with several sets of SNMP
parameters.
3. Elements Of Procedure
The following sections describe the procedures followed by each type
of application when generating messages for transmission or when
processing received messages. Applications communicate with the
Dispatcher using the abstract service interfaces defined in
[RFC3411].
3.1. Command Generator Applications
A command generator initiates an SNMP request by calling the
Dispatcher using the following abstract service interface:
statusInformation = -- sendPduHandle if success
-- errorIndication if failure
sendPdu(
IN transportDomain -- transport domain to be used
IN transportAddress -- destination network address
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN expectResponse -- TRUE or FALSE
)
Where:
- The transportDomain is that of the destination of the message.
- The transportAddress is that of the destination of the message.
- The messageProcessingModel indicates which Message Processing Model
the application wishes to use.
- The securityModel is the security model that the application wishes
to use.
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RFC 3413 SNMP Applications December 2002
- The securityName is the security model independent name for the
principal on whose behalf the application wishes the message to be
generated.
- The securityLevel is the security level that the application wishes
to use.
- The contextEngineID specifies the location of the management
information it is requesting. Note that unless the request is
being sent to a proxy, this value will usually be equal to the
snmpEngineID value of the engine to which the request is being
sent.
- The contextName specifies the local context name for the management
information it is requesting.
- The pduVersion indicates the version of the PDU to be sent.
- The PDU is a value constructed by the command generator containing
the management operation that the command generator wishes to
perform.
- The expectResponse argument indicates that a response is expected.
The result of the sendPdu interface indicates whether the PDU was
successfully sent. If it was successfully sent, the returned value
will be a sendPduHandle. The command generator should store the
sendPduHandle so that it can correlate a response to the original
request.
The Dispatcher is responsible for delivering the response to a
particular request to the correct command generator application. The
abstract service interface used is:
processResponsePdu( -- process Response PDU
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model in use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security
IN contextEngineID -- data from/at this SNMP entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN statusInformation -- success or errorIndication
IN sendPduHandle -- handle from sendPdu
)
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RFC 3413 SNMP Applications December 2002
Where:
- The messageProcessingModel is the value from the received response.
- The securityModel is the value from the received response.
- The securityName is the value from the received response.
- The securityLevel is the value from the received response.
- The contextEngineID is the value from the received response.
- The contextName is the value from the received response.
- The pduVersion indicates the version of the PDU in the received
response.
- The PDU is the value from the received response.
- The statusInformation indicates success or failure in receiving the
response.
- The sendPduHandle is the value returned by the sendPdu call which
generated the original request to which this is a response.
The procedure when a command generator receives a message is as
follows:
(1) If the received values of messageProcessingModel, securityModel,
securityName, contextEngineID, contextName, and pduVersion are
not all equal to the values used in the original request, the
response is discarded.
(2) The operation type, request-id, error-status, error-index, and
variable-bindings are extracted from the PDU and saved. If the
request-id is not equal to the value used in the original
request, the response is discarded.
(3) At this point, it is up to the application to take an appropriate
action. The specific action is implementation dependent. If the
statusInformation indicates that the request failed, an
appropriate action might be to attempt to transmit the request
again, or to notify the person operating the application that a
failure occurred.
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RFC 3413 SNMP Applications December 20023.2. Command Responder Applications
Before a command responder application can process messages, it must
first associate itself with an SNMP engine. The abstract service
interface used for this purpose is:
statusInformation = -- success or errorIndication
registerContextEngineID(
IN contextEngineID -- take responsibility for this one
IN pduType -- the pduType(s) to be registered
)
Where:
- The statusInformation indicates success or failure of the
registration attempt.
- The contextEngineID is equal to the snmpEngineID of the SNMP engine
with which the command responder is registering.
- The pduType indicates a Read-Class and/or Write-Class PDU.
Note that if another command responder application is already
registered with an SNMP engine, any further attempts to register with
the same contextEngineID and pduType will be denied. This implies
that separate command responder applications could register
separately for the various pdu types. However, in practice this is
undesirable, and only a single command responder application should
be registered with an SNMP engine at any given time.
A command responder application can disassociate with an SNMP engine
using the following abstract service interface:
unregisterContextEngineID(
IN contextEngineID -- give up responsibility for this one
IN pduType -- the pduType(s) to be unregistered
)
Where:
- The contextEngineID is equal to the snmpEngineID of the SNMP engine
with which the command responder is cancelling the registration.
- The pduType indicates a Read-Class and/or Write-Class PDU.
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RFC 3413 SNMP Applications December 2002
Once the command responder has registered with the SNMP engine, it
waits to receive SNMP messages. The abstract service interface used
for receiving messages is:
processPdu( -- process Request/Notification PDU
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model in use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security
IN contextEngineID -- data from/at this SNMP entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN maxSizeResponseScopedPDU -- maximum size of the Response PDU
IN stateReference -- reference to state information
) -- needed when sending a response
Where:
- The messageProcessingModel indicates which Message Processing Model
received and processed the message.
- The securityModel is the value from the received message.
- The securityName is the value from the received message.
- The securityLevel is the value from the received message.
- The contextEngineID is the value from the received message.
- The contextName is the value from the received message.
- The pduVersion indicates the version of the PDU in the received
message.
- The PDU is the value from the received message.
- The maxSizeResponseScopedPDU is the maximum allowable size of a
ScopedPDU containing a Response PDU (based on the maximum message
size that the originator of the message can accept).
- The stateReference is a value which references cached information
about each received request message. This value must be returned
to the Dispatcher in order to generate a response.
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RFC 3413 SNMP Applications December 2002
The procedure when a message is received is as follows:
(1) The operation type is determined from the ASN.1 tag value
associated with the PDU parameter. The operation type should
always be one of the types previously registered by the
application.
(2) The request-id is extracted from the PDU and saved.
(3) Any PDU type specific parameters are extracted from the PDU and
saved (for example, if the PDU type is an SNMPv2 GetBulk PDU, the
non-repeaters and max-repetitions values are extracted).
(4) The variable-bindings are extracted from the PDU and saved.
(5) The management operation represented by the PDU type is performed
with respect to the relevant MIB view within the context named by
the contextName (for an SNMPv2 PDU type, the operation is
performed according to the procedures set forth in [RFC1905]).
The relevant MIB view is determined by the securityLevel,
securityModel, contextName, securityName, and the class of the
PDU type. To determine whether a particular object instance is
within the relevant MIB view, the following abstract service
interface is called:
statusInformation = -- success or errorIndication
isAccessAllowed(
IN securityModel -- Security Model in use
IN securityName -- principal who wants to access
IN securityLevel -- Level of Security
IN viewType -- read, write, or notify view
IN contextName -- context containing variableName
IN variableName -- OID for the managed object
)
Where:
- The securityModel is the value from the received message.
- The securityName is the value from the received message.
- The securityLevel is the value from the received message.
- The viewType indicates whether the PDU type is a Read-Class or
Write-Class operation.
- The contextName is the value from the received message.
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RFC 3413 SNMP Applications December 2002
- The variableName is the object instance of the variable for
which access rights are to be checked.
Normally, the result of the management operation will be a new
PDU value, and processing will continue in step (6) below.
However, at any time during the processing of the management
operation:
- If the isAccessAllowed ASI returns a noSuchView, noAccessEntry,
or noGroupName error, processing of the management operation is
halted, a PDU value is constructed using the values from the
originally received PDU, but replacing the error-status with an
authorizationError code, and error-index value of 0, and
control is passed to step (6) below.
- If the isAccessAllowed ASI returns an otherError, processing of
the management operation is halted, a different PDU value is
constructed using the values from the originally received PDU,
but replacing the error-status with a genError code and the
error-index with the index of the failed variable binding, and
control is passed to step (6) below.
- If the isAccessAllowed ASI returns a noSuchContext error,
processing of the management operation is halted, no result PDU
is generated, the snmpUnknownContexts counter is incremented,
and control is passed to step (6) below for generation of a
report message.
- If the context named by the contextName parameter is
unavailable, processing of the management operation is halted,
no result PDU is generated, the snmpUnavailableContexts counter
is incremented, and control is passed to step (6) below for
generation of a report message.
(6) The Dispatcher is called to generate a response or report
message. The abstract service interface is:
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RFC 3413 SNMP Applications December 2002
returnResponsePdu(
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model in use
IN securityName -- on behalf of this principal
IN securityLevel -- same as on incoming request
IN contextEngineID -- data from/at this SNMP entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN maxSizeResponseScopedPDU -- maximum size of the Response PDU
IN stateReference -- reference to state information
-- as presented with the request
IN statusInformation -- success or errorIndication
) -- error counter OID/value if error
Where:
- The messageProcessingModel is the value from the processPdu
call.
- The securityModel is the value from the processPdu call.
- The securityName is the value from the processPdu call.
- The securityLevel is the value from the processPdu call.
- The contextEngineID is the value from the processPdu call.
- The contextName is the value from the processPdu call.
- The pduVersion indicates the version of the PDU to be returned.
If no result PDU was generated, the pduVersion is an undefined
value.
- The PDU is the result generated in step (5) above. If no
result PDU was generated, the PDU is an undefined value.
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value from the processPdu call.
- The statusInformation either contains an indication that no
error occurred and that a response should be generated, or
contains an indication that an error occurred along with the
OID and counter value of the appropriate error counter object.
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RFC 3413 SNMP Applications December 2002
Note that a command responder application should always call the
returnResponsePdu abstract service interface, even in the event of an
error such as a resource allocation error. In the event of such an
error, the PDU value passed to returnResponsePdu should contain
appropriate values for errorStatus and errorIndex.
Note that the text above describes situations where the
snmpUnknownContexts counter is incremented, and where the
snmpUnavailableContexts counter is incremented. The difference
between these is that the snmpUnknownContexts counter is incremented
when a request is received for a context which is unknown to the SNMP
entity. The snmpUnavailableContexts counter is incremented when a
request is received for a context which is known to the SNMP entity,
but is currently unavailable. Determining when a context is
unavailable is implementation specific, and some implementations may
never encounter this situation, and so may never increment the
snmpUnavailableContexts counter.
3.3. Notification Originator Applications
A notification originator application generates SNMP messages
containing Notification-Class PDUs (for example, SNMPv2-Trap PDUs or
Inform PDUs). There is no requirement as to what specific types of
Notification-Class PDUs a particular implementation must be capable
of generating.
Notification originator applications require a mechanism for
identifying the management targets to which notifications should be
sent. The particular mechanism used is implementation dependent.
However, if an implementation makes the configuration of management
targets SNMP manageable, it MUST use the SNMP-TARGET-MIB module
described in this document.
When a notification originator wishes to generate a notification, it
must first determine in which context the information to be conveyed
in the notification exists, i.e., it must determine the
contextEngineID and contextName. It must then determine the set of
management targets to which the notification should be sent. The
application must also determine, for each management target, what
specific PDU type the notification message should contain, and if it
is to contain a Confirmed-Class PDU, the number of retries and
retransmission algorithm.
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RFC 3413 SNMP Applications December 2002
The mechanism by which a notification originator determines this
information is implementation dependent. Once the application has
determined this information, the following procedure is performed for
each management target:
(1) Any appropriate filtering mechanisms are applied to determine
whether the notification should be sent to the management target.
If such filtering mechanisms determine that the notification
should not be sent, processing continues with the next management
target. Otherwise,
(2) The appropriate set of variable-bindings is retrieved from local
MIB instrumentation within the relevant MIB view. The relevant
MIB view is determined by the securityLevel, securityModel,
contextName, and securityName of the management target. To
determine whether a particular object instance is within the
relevant MIB view, the isAccessAllowed abstract service interface
is used, in the same manner as described in the preceding
section, except that the viewType indicates a Notification-Class
operation. If the statusInformation returned by isAccessAllowed
does not indicate accessAllowed, the notification is not sent to
the management target.
(3) The NOTIFICATION-TYPE OBJECT IDENTIFIER of the notification (this
is the value of the element of the variable bindings whose name
is snmpTrapOID.0, i.e., the second variable binding) is checked
using the isAccessAllowed abstract service interface, using the
same parameters used in the preceding step. If the
statusInformation returned by isAccessAllowed does not indicate
accessAllowed, the notification is not sent to the management
target.
(4) A PDU is constructed using a locally unique request-id value, a
PDU type as determined by the implementation, an error-status and
error-index value of 0, and the variable-bindings supplied
previously in step (2).
(5) If the notification contains an Unconfirmed-Class PDU, the
Dispatcher is called using the following abstract service
interface:
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RFC 3413 SNMP Applications December 2002
statusInformation = -- sendPduHandle if success
-- errorIndication if failure
sendPdu(
IN transportDomain -- transport domain to be used
IN transportAddress -- destination network address
IN messageProcessingModel -- typically, SNMP version
IN securityModel -- Security Model to use
IN securityName -- on behalf of this principal
IN securityLevel -- Level of Security requested
IN contextEngineID -- data from/at this entity
IN contextName -- data from/in this context
IN pduVersion -- the version of the PDU
IN PDU -- SNMP Protocol Data Unit
IN expectResponse -- TRUE or FALSE
)
Where:
- The transportDomain is that of the management target.
- The transportAddress is that of the management target.
- The messageProcessingModel is that of the management target.
- The securityModel is that of the management target.
- The securityName is that of the management target.
- The securityLevel is that of the management target.
- The contextEngineID is the value originally determined for the
notification.
- The contextName is the value originally determined for the
notification.
- The pduVersion is the version of the PDU to be sent.
- The PDU is the value constructed in step (4) above.
- The expectResponse argument indicates that no response is
expected.
Otherwise,
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RFC 3413 SNMP Applications December 2002
(6) If the notification contains a Confirmed-Class PDU, then:
a) The Dispatcher is called using the sendPdu abstract service
interface as described in step (5) above, except that the
expectResponse argument indicates that a response is expected.
b) The application caches information about the management
target.
c) If a response is received within an appropriate time interval
from the transport endpoint of the management target, the
notification is considered acknowledged and the cached
information is deleted. Otherwise,
d) If a response is not received within an appropriate time
period, or if a report indication is received, information
about the management target is retrieved from the cache, and
steps a) through d) are repeated. The number of times these
steps are repeated is equal to the previously determined retry
count. If this retry count is exceeded, the acknowledgement
of the notification is considered to have failed, and
processing of the notification for this management target is
halted. Note that some report indications might be considered
a failure. Such report indications should be interpreted to
mean that the acknowledgement of the notification has failed,
and that steps a) through d) need not be repeated.
Responses to Confirmed-Class PDU notifications will be received via
the processResponsePdu abstract service interface.
To summarize, the steps that a notification originator follows when
determining where to send a notification are:
- Determine the targets to which the notification should be sent.
- Apply any required filtering to the list of targets.
- Determine which targets are authorized to receive the notification.
3.4. Notification Receiver Applications
Notification receiver applications receive SNMP Notification messages
from the Dispatcher. Before any messages can be received, the
notification receiver must register with the Dispatcher using the
registerContextEngineID abstract service interface. The parameters
used are:
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RFC 3413 SNMP Applications December 2002
- The contextEngineID is an undefined 'wildcard' value.
Notifications are delivered to a registered notification receiver
regardless of the contextEngineID contained in the notification
message.
- The pduType indicates the type of notifications that the
application wishes to receive (for example, SNMPv2-Trap PDUs or
Inform PDUs).
Once the notification receiver has registered with the Dispatcher,
messages are received using the processPdu abstract service
interface. Parameters are:
- The messageProcessingModel indicates which Message Processing Model
received and processed the message.
- The securityModel is the value from the received message.
- The securityName is the value from the received message.
- The securityLevel is the value from the received message.
- The contextEngineID is the value from the received message.
- The contextName is the value from the received message.
- The pduVersion indicates the version of the PDU in the received
message.
- The PDU is the value from the received message.
- The maxSizeResponseScopedPDU is the maximum allowable size of a
ScopedPDU containing a Response PDU (based on the maximum message
size that the originator of the message can accept).
- If the message contains an Unconfirmed-Class PDU, the
stateReference is undefined and unused. Otherwise, the
stateReference is a value which references cached information about
the notification. This value must be returned to the Dispatcher in
order to generate a response.
When an Unconfirmed-Class PDU is delivered to a notification receiver
application, it first extracts the SNMP operation type, request-id,
error-status, error-index, and variable-bindings from the PDU. After
this, processing depends on the particular implementation.
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RFC 3413 SNMP Applications December 2002
When a Confirmed-Class PDU is received, the notification receiver
application follows the following procedure:
(1) The PDU type, request-id, error-status, error-index, and
variable-bindings are extracted from the PDU.
(2) A Response-Class PDU is constructed using the extracted
request-id and variable-bindings, and with error-status and
error-index both set to 0.
(3) The Dispatcher is called to generate a response message using the
returnResponsePdu abstract service interface. Parameters are:
- The messageProcessingModel is the value from the processPdu
call.
- The securityModel is the value from the processPdu call.
- The securityName is the value from the processPdu call.
- The securityLevel is the value from the processPdu call.
- The contextEngineID is the value from the processPdu call.
- The contextName is the value from the processPdu call.
- The pduVersion indicates the version of the PDU to be returned.
- The PDU is the result generated in step (2) above.
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value from the processPdu call.
- The statusInformation indicates that no error occurred and that
a response should be generated.
(4) After this, processing depends on the particular implementation.
3.5. Proxy Forwarder Applications
A proxy forwarder application deals with forwarding SNMP messages.
There are four basic types of messages which a proxy forwarder
application may need to forward. These are grouped according to the
class of PDU type contained in a message. The four basic types of
messages are:
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RFC 3413 SNMP Applications December 2002
- Those containing Read-Class or Write-Class PDU types (for example,
Get, GetNext, GetBulk, and Set PDU types). These deal with
requesting or modifying information located within a particular
context.
- Those containing Notification-Class PDU types (for example,
SNMPv2-Trap and Inform PDU types). These deal with notifications
concerning information located within a particular context.
- Those containing a Response-Class PDU type. Forwarding of
Response-Class PDUs always occurs as a result of receiving a
response to a previously forwarded message.
- Those containing Internal-Class PDU types (for example, a Report
PDU). Forwarding of Internal-Class PDU types always occurs as a
result of receiving an Internal-Class PDU in response to a
previously forwarded message.
For the first type, the proxy forwarder's role is to deliver a
request for management information to an SNMP engine which is
"closer" or "downstream in the path" to the SNMP engine which has
access to that information, and to deliver the response containing
the information back to the SNMP engine from which the request was
received. The context information in a request is used to determine
which SNMP engine has access to the requested information, and this
is used to determine where and how to forward the request.
For the second type, the proxy forwarder's role is to determine which
SNMP engines should receive notifications about management
information from a particular location. The context information in a
notification message determines the location to which the information
contained in the notification applies. This is used to determine
which SNMP engines should receive notification about this
information.
For the third type, the proxy forwarder's role is to determine which
previously forwarded request or notification (if any) the response
matches, and to forward the response back to the initiator of the
request or notification.
For the fourth type, the proxy forwarder's role is to determine which
previously forwarded request or notification (if any) the Internal-
Class PDU matches, and to forward the Internal-Class PDU back to the
initiator of the request or notification.
Levi, et. al. Standards Track [Page 20]

RFC 3413 SNMP Applications December 2002
When forwarding messages, a proxy forwarder application must perform
a translation of incoming management target information into outgoing
management target information. How this translation is performed is
implementation specific. In many cases, this will be driven by a
preconfigured translation table. If a proxy forwarder application
makes the contents of this table SNMP manageable, it MUST use the
SNMP-PROXY-MIB module defined in this document.
3.5.1. Request Forwarding
There are two phases for request forwarding. First, the incoming
request needs to be passed through the proxy application. Then, the
resulting response needs to be passed back. These phases are
described in the following two sections.
3.5.1.1. Processing an Incoming Request
A proxy forwarder application that wishes to forward request messages
must first register with the Dispatcher using the
registerContextEngineID abstract service interface. The proxy
forwarder must register each contextEngineID for which it wishes to
forward messages, as well as for each pduType. Note that as the
configuration of a proxy forwarder is changed, the particular
contextEngineID values for which it is forwarding may change. The
proxy forwarder should call the registerContextEngineID and
unregisterContextEngineID abstract service interfaces as needed to
reflect its current configuration.
A proxy forwarder application should never attempt to register a
value of contextEngineID which is equal to the snmpEngineID of the
SNMP engine to which the proxy forwarder is associated.
Once the proxy forwarder has registered for the appropriate
contextEngineID values, it can start processing messages. The
following procedure is used:
(1) A message is received using the processPdu abstract service
interface. The incoming management target information received
from the processPdu interface is translated into outgoing
management target information. Note that this translation may
vary for different values of contextEngineID and/or contextName.
The translation should result in a single management target.
(2) If appropriate outgoing management target information cannot be
found, the proxy forwarder increments the snmpProxyDrops counter
[RFC1907], and then calls the Dispatcher using the
returnResponsePdu abstract service interface. Parameters are:
Levi, et. al. Standards Track [Page 21]

RFC 3413 SNMP Applications December 2002
- The messageProcessingModel is the value from the processPdu
call.
- The securityModel is the value from the processPdu call.
- The securityName is the value from the processPdu call.
- The securityLevel is the value from the processPdu call.
- The contextEngineID is the value from the processPdu call.
- The contextName is the value from the processPdu call.
- The pduVersion is the value from the processPdu call.
- The PDU is an undefined value.
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value from the processPdu call.
- The statusInformation indicates that an error occurred and
includes the OID and value of the snmpProxyDrops object.
Processing of the message stops at this point. Otherwise,
(3) A new PDU is constructed. A unique value of request-id should be
used in the new PDU (this value will enable a subsequent response
message to be correlated with this request). The remainder of
the new PDU is identical to the received PDU, unless the incoming
SNMP version and the outgoing SNMP version support different PDU
versions, in which case the proxy forwarder may need to perform a
translation on the PDU. (A method for performing such a
translation is described in [RFC2576].)
(4) The proxy forwarder calls the Dispatcher to generate the
forwarded message, using the sendPdu abstract service interface.
The parameters are:
- The transportDomain is that of the outgoing management target.
- The transportAddress is that of the outgoing management target.
- The messageProcessingModel is that of the outgoing management
target.
- The securityModel is that of the outgoing management target.
Levi, et. al. Standards Track [Page 22]

RFC 3413 SNMP Applications December 2002
- The securityName is that of the outgoing management target.
- The securityLevel is that of the outgoing management target.
- The contextEngineID is the value from the processPdu call.
- The contextName is the value from the processPdu call.
- The pduVersion is the version of the PDU to be sent.
- The PDU is the value constructed in step (3) above.
- The expectResponse argument indicates that a response is
expected. If the sendPdu call is unsuccessful, the proxy
forwarder performs the steps described in (2) above.
Otherwise:
(5) The proxy forwarder caches the following information in order to
match an incoming response to the forwarded request:
- The sendPduHandle returned from the call to sendPdu,
- The request-id from the received PDU.
- The contextEngineID,
- The contextName,
- The stateReference,
- The incoming management target information,
- The outgoing management information,
- Any other information needed to match an incoming response to
the forwarded request.
If this information cannot be cached (possibly due to a lack of
resources), the proxy forwarder performs the steps described in
(2) above. Otherwise:
(6) Processing of the request stops until a response to the forwarded
request is received, or until an appropriate time interval has
expired. If this time interval expires before a response has
been received, the cached information about this request is
removed.
Levi, et. al. Standards Track [Page 23]

RFC 3413 SNMP Applications December 20023.5.1.2. Processing an Incoming Response
A proxy forwarder follows the following procedure when an
incoming response is received:
(1) The incoming response is received using the processResponsePdu
interface. The proxy forwarder uses the received parameters to
locate an entry in its cache of pending forwarded requests. This
is done by matching the received parameters with the cached
values of sendPduHandle, contextEngineID, contextName, outgoing
management target information, and the request-id contained in
the received PDU (the proxy forwarder must extract the request-id
for this purpose). If an appropriate cache entry cannot be
found, processing of the response is halted. Otherwise:
(2) The cache information is extracted, and removed from the cache.
(3) A new Response-Class PDU is constructed, using the request-id
value from the original forwarded request (as extracted from the
cache). All other values are identical to those in the received
Response-Class PDU, unless the incoming SNMP version and the
outgoing SNMP version support different PDU versions, in which
case the proxy forwarder may need to perform a translation on the
PDU. (A method for performing such a translation is described in
[RFC2576].)
(4) The proxy forwarder calls the Dispatcher using the
returnResponsePdu abstract service interface. Parameters are:
- The messageProcessingModel indicates the Message Processing
Model by which the original incoming message was processed.
- The securityModel is that of the original incoming management
target extracted from the cache.
- The securityName is that of the original incoming management
target extracted from the cache.
- The securityLevel is that of the original incoming management
target extracted from the cache.
- The contextEngineID is the value extracted from the cache.
- The contextName is the value extracted from the cache.
- The pduVersion indicates the version of the PDU to be returned.
- The PDU is the (possibly translated) Response PDU.
Levi, et. al. Standards Track [Page 24]

RFC 3413 SNMP Applications December 2002
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value extracted from the cache.
- The statusInformation indicates that no error occurred and that
a Response PDU message should be generated.
3.5.1.3. Processing an Incoming Internal-Class PDU
A proxy forwarder follows the following procedure when an incoming
Internal-Class PDU is received:
(1) The incoming Internal-Class PDU is received using the
processResponsePdu interface. The proxy forwarder uses the
received parameters to locate an entry in its cache of pending
forwarded requests. This is done by matching the received
parameters with the cached values of sendPduHandle. If an
appropriate cache entry cannot be found, processing of the
Internal-Class PDU is halted. Otherwise:
(2) The cache information is extracted, and removed from the cache.
(3) If the original incoming management target information indicates
an SNMP version which does not support Report PDUs, processing of
the Internal-Class PDU is halted.
(4) The proxy forwarder calls the Dispatcher using the
returnResponsePdu abstract service interface. Parameters are:
- The messageProcessingModel indicates the Message Processing
Model by which the original incoming message was processed.
- The securityModel is that of the original incoming management
target extracted from the cache.
- The securityName is that of the original incoming management
target extracted from the cache.
- The securityLevel is that of the original incoming management
target extracted from the cache.
- The contextEngineID is the value extracted from the cache.
- The contextName is the value extracted from the cache.
- The pduVersion indicates the version of the PDU to be returned.
Levi, et. al. Standards Track [Page 25]

RFC 3413 SNMP Applications December 2002
- The PDU is unused.
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value extracted from the cache.
- The statusInformation contains values specific to the
Internal-Class PDU type (for example, for a Report PDU, the
statusInformation contains the contextEngineID, contextName,
counter OID, and counter value received in the incoming Report
PDU).
3.5.2. Notification Forwarding
A proxy forwarder receives notifications in the same manner as a
notification receiver application, using the processPdu abstract
service interface. The following procedure is used when a
notification is received:
(1) The incoming management target information received from the
processPdu interface is translated into outgoing management
target information. Note that this translation may vary for
different values of contextEngineID and/or contextName. The
translation may result in multiple management targets.
(2) If appropriate outgoing management target information cannot be
found and the notification was an Unconfirmed-Class PDU,
processing of the notification is halted. If appropriate
outgoing management target information cannot be found and the
notification was a Confirmed-Class PDU, the proxy forwarder
increments the snmpProxyDrops object, and calls the Dispatcher
using the returnResponsePdu abstract service interface. The
parameters are:
- The messageProcessingModel is the value from the processPdu
call.
- The securityModel is the value from the processPdu call.
- The securityName is the value from the processPdu call.
- The securityLevel is the value from the processPdu call.
- The contextEngineID is the value from the processPdu call.
- The contextName is the value from the processPdu call.
Levi, et. al. Standards Track [Page 26]

RFC 3413 SNMP Applications December 2002
- The pduVersion is the value from the processPdu call.
- The PDU is an undefined and unused value.
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value from the processPdu call.
- The statusInformation indicates that an error occurred and that
a Report message should be generated.
Processing of the message stops at this point. Otherwise,
(3) The proxy forwarder generates a notification using the procedures
described in the preceding section on Notification Originators,
with the following exceptions:
- The contextEngineID and contextName values from the original
received notification are used.
- The outgoing management targets previously determined are used.
- No filtering mechanisms are applied.
- The variable-bindings from the original received notification
are used, rather than retrieving variable-bindings from local
MIB instrumentation. In particular, no access-control is
applied to these variable-bindings, nor to the value of the
variable-binding containing snmpTrapOID.0.
- If the original notification contains a Confirmed-Class PDU,
then any outgoing management targets for which the outgoing
SNMP version does not support any PDU types that are both
Notification-Class and Confirmed-Class PDUs will not be used
when generating the forwarded notifications.
- If, for any of the outgoing management targets, the incoming
SNMP version and the outgoing SNMP version support different
PDU versions, the proxy forwarder may need to perform a
translation on the PDU. (A method for performing such a
translation is described in [RFC2576].)
(4) If the original received notification contains an
Unconfirmed-Class PDU, processing of the notification is now
completed. Otherwise, the original received notification must
contain Confirmed-Class PDU, and processing continues.
Levi, et. al. Standards Track [Page 27]

RFC 3413 SNMP Applications December 2002
(5) If the forwarded notifications included any Confirmed-Class PDUs,
processing continues when the procedures described in the section
for Notification Originators determine that either:
- None of the generated notifications containing Confirmed-Class
PDUs have been successfully acknowledged within the longest of
the time intervals, in which case processing of the original
notification is halted, or,
- At least one of the generated notifications containing
Confirmed-Class PDUs is successfully acknowledged, in which
case a response to the original received notification
containing an Confirmed-Class PDU is generated as described in
the following steps.
(6) A Response-Class PDU is constructed, using the values of
request-id and variable-bindings from the original received
Notification-Class PDU, and error-status and error-index values
of 0.
(7) The Dispatcher is called using the returnResponsePdu abstract
service interface. Parameters are:
- The messageProcessingModel is the value from the processPdu
call.
- The securityModel is the value from the processPdu call.
- The securityName is the value from the processPdu call.
- The securityLevel is the value from the processPdu call.
- The contextEngineID is the value from the processPdu call.
- The contextName is the value from the processPdu call.
- The pduVersion indicates the version of the PDU constructed in
step (6) above.
- The PDU is the value constructed in step (6) above.
- The maxSizeResponseScopedPDU is a local value indicating the
maximum size of a ScopedPDU that the application can accept.
- The stateReference is the value from the processPdu call.
- The statusInformation indicates that no error occurred and that
a Response-Class PDU message should be generated.
Levi, et. al. Standards Track [Page 28]

RFC 3413 SNMP Applications December 20024. The Structure of the MIB Modules
There are three separate MIB modules described in this document, the
management target MIB, the notification MIB, and the proxy MIB. The
following sections describe the structure of these three MIB modules.
The use of these MIBs by particular types of applications is
described later in this document:
- The use of the management target MIB and the notification MIB in
notification originator applications is described in section 5.
- The use of the notification MIB for filtering notifications in
notification originator applications is described in section 6.
- The use of the management target MIB and the proxy MIB in proxy
forwarding applications is described in section 7.
4.1. The Management Target MIB Module
The SNMP-TARGET-MIB module contains objects for defining management
targets. It consists of two tables and conformance/compliance
statements.
The first table, the snmpTargetAddrTable, contains information about
transport domains and addresses. It also contains an object,
snmpTargetAddrTagList, which provides a mechanism for grouping
entries.
The second table, the snmpTargetParamsTable, contains information
about SNMP version and security information to be used when sending
messages to particular transport domains and addresses.
The Management Target MIB is intended to provide a general-purpose
mechanism for specifying transport address, and for specifying
parameters of SNMP messages generated by an SNMP entity. It is used
within this document for generation of notifications and for proxy
forwarding. However, it may be used for other purposes. If another
document makes use of this MIB, that document is responsible for
specifying how it is used. For example, [RFC2576] uses this MIB for
source address validation of SNMPv1 messages.
4.1.1. Tag Lists
The snmpTargetAddrTagList object is used for grouping entries in the
snmpTargetAddrTable. The value of this object contains a list of tag
values which are used to select target addresses to be used for a
particular operation.
Levi, et. al. Standards Track [Page 29]

RFC 3413 SNMP Applications December 2002
A tag value, which may also be used in MIB objects other than
snmpTargetAddrTagList, is an arbitrary string of octets, but may not
contain a delimiter character. Delimiter characters are defined to
be one of the following characters:
- An ASCII space character (0x20).
- An ASCII TAB character (0x09).
- An ASCII carriage return (CR) character (0x0D).
- An ASCII line feed (LF) character (0x0A).
In addition, a tag value within a tag list may not have a zero
length. Generally, a particular MIB object may contain either
- a zero-length octet string representing an empty list, or
- a single tag value, in which case the value of the MIB object may
not contain a delimiter character, or
- a list of tag values, separated by single delimiter characters.
For a list of tag values, these constraints imply certain
restrictions on the value of a MIB object:
- There cannot be a leading or trailing delimiter character.
- There cannot be multiple adjacent delimiter characters.
4.1.2. Definitions
SNMP-TARGET-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY,
OBJECT-TYPE,
snmpModules,
Counter32,
Integer32
FROM SNMPv2-SMI
TEXTUAL-CONVENTION,
TDomain,
TAddress,
TimeInterval,
RowStatus,
StorageType,
Levi, et. al. Standards Track [Page 30]

RFC 3413 SNMP Applications December 2002
Roseville, Minnesota 55113
EMail: paul_meyer@securecomputing.com
Phone: +1 651 628 1592
Co-editor: Bob Stewart
Retired"
DESCRIPTION
"This MIB module defines MIB objects which provide
mechanisms to remotely configure the parameters used
by an SNMP entity for the generation of SNMP messages.
Copyright (C) The Internet Society (2002). This
version of this MIB module is part of RFC 3413;
see the RFC itself for full legal notices.
"
REVISION "200210140000Z" -- 14 October 2002
DESCRIPTION "Fixed DISPLAY-HINTS for UTF-8 strings, fixed hex
value of LF characters, clarified meaning of zero
length tag values, improved tag list examples.
Published as RFC 3413."
REVISION "199808040000Z" -- 4 August 1998
DESCRIPTION "Clarifications, published as
RFC 2573."
REVISION "199707140000Z" -- 14 July 1997
DESCRIPTION "The initial revision, published as RFC2273."
::= { snmpModules 12 }
snmpTargetObjects OBJECT IDENTIFIER ::= { snmpTargetMIB 1 }
snmpTargetConformance OBJECT IDENTIFIER ::= { snmpTargetMIB 3 }
SnmpTagValue ::= TEXTUAL-CONVENTION
DISPLAY-HINT "255t"
STATUS current
DESCRIPTION
"An octet string containing a tag value.
Tag values are preferably in human-readable form.
To facilitate internationalization, this information
is represented using the ISO/IEC IS 10646-1 character
set, encoded as an octet string using the UTF-8
character encoding scheme described in RFC 2279.
Since additional code points are added by amendments
to the 10646 standard from time to time,
implementations must be prepared to encounter any code
point from 0x00000000 to 0x7fffffff.
The use of control codes should be avoided, and certain
Levi, et. al. Standards Track [Page 32]

RFC 3413 SNMP Applications December 2002
control codes are not allowed as described below.
For code points not directly supported by user
interface hardware or software, an alternative means
of entry and display, such as hexadecimal, may be
provided.
For information encoded in 7-bit US-ASCII, the UTF-8
representation is identical to the US-ASCII encoding.
Note that when this TC is used for an object that
is used or envisioned to be used as an index, then a
SIZE restriction must be specified so that the number
of sub-identifiers for any object instance does not
exceed the limit of 128, as defined by [RFC1905].
An object of this type contains a single tag value
which is used to select a set of entries in a table.
A tag value is an arbitrary string of octets, but
may not contain a delimiter character. Delimiter
characters are defined to be one of the following:
- An ASCII space character (0x20).
- An ASCII TAB character (0x09).
- An ASCII carriage return (CR) character (0x0D).
- An ASCII line feed (LF) character (0x0A).
Delimiter characters are used to separate tag values
in a tag list. An object of this type may only
contain a single tag value, and so delimiter
characters are not allowed in a value of this type.
Note that a tag value of 0 length means that no tag is
defined. In other words, a tag value of 0 length would
never match anything in a tag list, and would never
select any table entries.
Some examples of valid tag values are:
- 'acme'
- 'router'
- 'host'
Levi, et. al. Standards Track [Page 33]

RFC 3413 SNMP Applications December 2002
The use of a tag value to select table entries is
application and MIB specific."
SYNTAX OCTET STRING (SIZE (0..255))
SnmpTagList ::= TEXTUAL-CONVENTION
DISPLAY-HINT "255t"
STATUS current
DESCRIPTION
"An octet string containing a list of tag values.
Tag values are preferably in human-readable form.
To facilitate internationalization, this information
is represented using the ISO/IEC IS 10646-1 character
set, encoded as an octet string using the UTF-8
character encoding scheme described in RFC 2279.
Since additional code points are added by amendments
to the 10646 standard from time to time,
implementations must be prepared to encounter any code
point from 0x00000000 to 0x7fffffff.
The use of control codes should be avoided, except as
described below.
For code points not directly supported by user
interface hardware or software, an alternative means
of entry and display, such as hexadecimal, may be
provided.
For information encoded in 7-bit US-ASCII, the UTF-8
representation is identical to the US-ASCII encoding.
An object of this type contains a list of tag values
which are used to select a set of entries in a table.
A tag value is an arbitrary string of octets, but
may not contain a delimiter character. Delimiter
characters are defined to be one of the following:
- An ASCII space character (0x20).
- An ASCII TAB character (0x09).
- An ASCII carriage return (CR) character (0x0D).
- An ASCII line feed (LF) character (0x0A).
Delimiter characters are used to separate tag values
Levi, et. al. Standards Track [Page 34]

RFC 3413 SNMP Applications December 2002
in a tag list. Only a single delimiter character may
occur between two tag values. A tag value may not
have a zero length. These constraints imply certain
restrictions on the contents of this object:
- There cannot be a leading or trailing delimiter
character.
- There cannot be multiple adjacent delimiter
characters.
Some examples of valid tag lists are:
- '' -- an empty list
- 'acme' -- list of one tag
- 'host router bridge' -- list of several tags
Note that although a tag value may not have a length of
zero, an empty string is still valid. This indicates
an empty list (i.e. there are no tag values in the list).
The use of the tag list to select table entries is
application and MIB specific. Typically, an application
will provide one or more tag values, and any entry
which contains some combination of these tag values
will be selected."
SYNTAX OCTET STRING (SIZE (0..255))
--
--
-- The snmpTargetObjects group
--
--
snmpTargetSpinLock OBJECT-TYPE
SYNTAX TestAndIncr
MAX-ACCESS read-write
STATUS current
DESCRIPTION
"This object is used to facilitate modification of table
entries in the SNMP-TARGET-MIB module by multiple
managers. In particular, it is useful when modifying
the value of the snmpTargetAddrTagList object.
The procedure for modifying the snmpTargetAddrTagList
object is as follows:
Levi, et. al. Standards Track [Page 35]

RFC 3413 SNMP Applications December 2002
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The locally arbitrary, but unique identifier associated
with this snmpTargetAddrEntry."
::= { snmpTargetAddrEntry 1 }
snmpTargetAddrTDomain OBJECT-TYPE
SYNTAX TDomain
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object indicates the transport type of the address
contained in the snmpTargetAddrTAddress object."
::= { snmpTargetAddrEntry 2 }
snmpTargetAddrTAddress OBJECT-TYPE
SYNTAX TAddress
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object contains a transport address. The format of
this address depends on the value of the
snmpTargetAddrTDomain object."
::= { snmpTargetAddrEntry 3 }
snmpTargetAddrTimeout OBJECT-TYPE
SYNTAX TimeInterval
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object should reflect the expected maximum round
trip time for communicating with the transport address
defined by this row. When a message is sent to this
address, and a response (if one is expected) is not
received within this time period, an implementation
may assume that the response will not be delivered.
Note that the time interval that an application waits
for a response may actually be derived from the value
of this object. The method for deriving the actual time
interval is implementation dependent. One such method
is to derive the expected round trip time based on a
particular retransmission algorithm and on the number
of timeouts which have occurred. The type of message may
also be considered when deriving expected round trip
times for retransmissions. For example, if a message is
being sent with a securityLevel that indicates both
Levi, et. al. Standards Track [Page 37]

RFC 3413 SNMP Applications December 2002
authentication and privacy, the derived value may be
increased to compensate for extra processing time spent
during authentication and encryption processing."
DEFVAL { 1500 }
::= { snmpTargetAddrEntry 4 }
snmpTargetAddrRetryCount OBJECT-TYPE
SYNTAX Integer32 (0..255)
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object specifies a default number of retries to be
attempted when a response is not received for a generated
message. An application may provide its own retry count,
in which case the value of this object is ignored."
DEFVAL { 3 }
::= { snmpTargetAddrEntry 5 }
snmpTargetAddrTagList OBJECT-TYPE
SYNTAX SnmpTagList
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object contains a list of tag values which are
used to select target addresses for a particular
operation."
DEFVAL { "" }
::= { snmpTargetAddrEntry 6 }
snmpTargetAddrParams OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(1..32))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The value of this object identifies an entry in the
snmpTargetParamsTable. The identified entry
contains SNMP parameters to be used when generating
messages to be sent to this transport address."
::= { snmpTargetAddrEntry 7 }
snmpTargetAddrStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The storage type for this conceptual row.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row."
Levi, et. al. Standards Track [Page 38]

RFC 3413 SNMP Applications December 2002
DEFVAL { nonVolatile }
::= { snmpTargetAddrEntry 8 }
snmpTargetAddrRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this conceptual row.
To create a row in this table, a manager must
set this object to either createAndGo(4) or
createAndWait(5).
Until instances of all corresponding columns are
appropriately configured, the value of the
corresponding instance of the snmpTargetAddrRowStatus
column is 'notReady'.
In particular, a newly created row cannot be made
active until the corresponding instances of
snmpTargetAddrTDomain, snmpTargetAddrTAddress, and
snmpTargetAddrParams have all been set.
The following objects may not be modified while the
value of this object is active(1):
- snmpTargetAddrTDomain
- snmpTargetAddrTAddress
An attempt to set these objects while the value of
snmpTargetAddrRowStatus is active(1) will result in
an inconsistentValue error."
::= { snmpTargetAddrEntry 9 }
snmpTargetParamsTable OBJECT-TYPE
SYNTAX SEQUENCE OF SnmpTargetParamsEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A table of SNMP target information to be used
in the generation of SNMP messages."
::= { snmpTargetObjects 3 }
snmpTargetParamsEntry OBJECT-TYPE
SYNTAX SnmpTargetParamsEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"A set of SNMP target information.
Levi, et. al. Standards Track [Page 39]

RFC 3413 SNMP Applications December 2002
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The securityName which identifies the Principal on
whose behalf SNMP messages will be generated using
this entry."
::= { snmpTargetParamsEntry 4 }
snmpTargetParamsSecurityLevel OBJECT-TYPE
SYNTAX SnmpSecurityLevel
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The Level of Security to be used when generating
SNMP messages using this entry."
::= { snmpTargetParamsEntry 5 }
snmpTargetParamsStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The storage type for this conceptual row.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row."
DEFVAL { nonVolatile }
::= { snmpTargetParamsEntry 6 }
snmpTargetParamsRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this conceptual row.
To create a row in this table, a manager must
set this object to either createAndGo(4) or
createAndWait(5).
Until instances of all corresponding columns are
appropriately configured, the value of the
corresponding instance of the snmpTargetParamsRowStatus
column is 'notReady'.
In particular, a newly created row cannot be made
active until the corresponding
snmpTargetParamsMPModel,
snmpTargetParamsSecurityModel,
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RFC 3413 SNMP Applications December 2002
snmpTargetParamsSecurityName,
and snmpTargetParamsSecurityLevel have all been set.
The following objects may not be modified while the
value of this object is active(1):
- snmpTargetParamsMPModel
- snmpTargetParamsSecurityModel
- snmpTargetParamsSecurityName
- snmpTargetParamsSecurityLevel
An attempt to set these objects while the value of
snmpTargetParamsRowStatus is active(1) will result in
an inconsistentValue error."
::= { snmpTargetParamsEntry 7 }
snmpUnavailableContexts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets received by the SNMP
engine which were dropped because the context
contained in the message was unavailable."
::= { snmpTargetObjects 4 }
snmpUnknownContexts OBJECT-TYPE
SYNTAX Counter32
MAX-ACCESS read-only
STATUS current
DESCRIPTION
"The total number of packets received by the SNMP
engine which were dropped because the context
contained in the message was unknown."
::= { snmpTargetObjects 5 }
--
--
-- Conformance information
--
--
snmpTargetCompliances OBJECT IDENTIFIER ::=
{ snmpTargetConformance 1 }
snmpTargetGroups OBJECT IDENTIFIER ::=
{ snmpTargetConformance 2 }
--
--
-- Compliance statements
Levi, et. al. Standards Track [Page 42]

RFC 3413 SNMP Applications December 2002
OBJECTS {
snmpUnavailableContexts,
snmpUnknownContexts
}
STATUS current
DESCRIPTION
"A collection of objects required for command responder
applications, used for counting error conditions."
::= { snmpTargetGroups 3 }
END
4.2. The Notification MIB Module
The SNMP-NOTIFICATION-MIB module contains objects for the remote
configuration of the parameters used by an SNMP entity for the
generation of notifications. It consists of three tables and
conformance/compliance statements. The first table, the
snmpNotifyTable, contains entries which select which entries in the
snmpTargetAddrTable should be used for generating notifications, and
the type of notifications to be generated.
The second table, the snmpNotifyFilterProfileTable, sparsely augments
the snmpTargetParamsTable with an object which is used to associate a
set of filters with a particular management target.
The third table, the snmpNotifyFilterTable, defines filters which are
used to limit the number of notifications which are generated using
particular management targets.
4.2.1. Definitions
SNMP-NOTIFICATION-MIB DEFINITIONS ::= BEGIN
IMPORTS
MODULE-IDENTITY,
OBJECT-TYPE,
snmpModules
FROM SNMPv2-SMI
RowStatus,
StorageType
FROM SNMPv2-TC
SnmpAdminString
FROM SNMP-FRAMEWORK-MIB
SnmpTagValue,
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RFC 3413 SNMP Applications December 2002
be generated for entries in the snmpTargetAddrTable
selected by the corresponding instance of
snmpNotifyTag. This value is only used when
generating notifications, and is ignored when
using the snmpTargetAddrTable for other purposes.
If the value of this object is trap(1), then any
messages generated for selected rows will contain
Unconfirmed-Class PDUs.
If the value of this object is inform(2), then any
messages generated for selected rows will contain
Confirmed-Class PDUs.
Note that if an SNMP entity only supports
generation of Unconfirmed-Class PDUs (and not
Confirmed-Class PDUs), then this object may be
read-only."
DEFVAL { trap }
::= { snmpNotifyEntry 3 }
snmpNotifyStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The storage type for this conceptual row.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row."
DEFVAL { nonVolatile }
::= { snmpNotifyEntry 4 }
snmpNotifyRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this conceptual row.
To create a row in this table, a manager must
set this object to either createAndGo(4) or
createAndWait(5)."
::= { snmpNotifyEntry 5 }
snmpNotifyFilterProfileTable OBJECT-TYPE
SYNTAX SEQUENCE OF SnmpNotifyFilterProfileEntry
MAX-ACCESS not-accessible
STATUS current
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RFC 3413 SNMP Applications December 2002
DESCRIPTION
"This table is used to associate a notification filter
profile with a particular set of target parameters."
::= { snmpNotifyObjects 2 }
snmpNotifyFilterProfileEntry OBJECT-TYPE
SYNTAX SnmpNotifyFilterProfileEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An entry in this table indicates the name of the filter
profile to be used when generating notifications using
the corresponding entry in the snmpTargetParamsTable.
Entries in the snmpNotifyFilterProfileTable are created
and deleted using the snmpNotifyFilterProfileRowStatus
object."
INDEX { IMPLIED snmpTargetParamsName }
::= { snmpNotifyFilterProfileTable 1 }
SnmpNotifyFilterProfileEntry ::= SEQUENCE {
snmpNotifyFilterProfileName SnmpAdminString,
snmpNotifyFilterProfileStorType StorageType,
snmpNotifyFilterProfileRowStatus RowStatus
}
snmpNotifyFilterProfileName OBJECT-TYPE
SYNTAX SnmpAdminString (SIZE(1..32))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The name of the filter profile to be used when generating
notifications using the corresponding entry in the
snmpTargetAddrTable."
::= { snmpNotifyFilterProfileEntry 1 }
snmpNotifyFilterProfileStorType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The storage type for this conceptual row.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row."
DEFVAL { nonVolatile }
::= { snmpNotifyFilterProfileEntry 2 }
snmpNotifyFilterProfileRowStatus OBJECT-TYPE
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RFC 3413 SNMP Applications December 2002
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this conceptual row.
To create a row in this table, a manager must
set this object to either createAndGo(4) or
createAndWait(5).
Until instances of all corresponding columns are
appropriately configured, the value of the
corresponding instance of the
snmpNotifyFilterProfileRowStatus column is 'notReady'.
In particular, a newly created row cannot be made
active until the corresponding instance of
snmpNotifyFilterProfileName has been set."
::= { snmpNotifyFilterProfileEntry 3 }
snmpNotifyFilterTable OBJECT-TYPE
SYNTAX SEQUENCE OF SnmpNotifyFilterEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The table of filter profiles. Filter profiles are used
to determine whether particular management targets should
receive particular notifications.
When a notification is generated, it must be compared
with the filters associated with each management target
which is configured to receive notifications, in order to
determine whether it may be sent to each such management
target.
A more complete discussion of notification filtering
can be found in section 6. of [SNMP-APPL]."
::= { snmpNotifyObjects 3 }
snmpNotifyFilterEntry OBJECT-TYPE
SYNTAX SnmpNotifyFilterEntry
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"An element of a filter profile.
Entries in the snmpNotifyFilterTable are created and
deleted using the snmpNotifyFilterRowStatus object."
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RFC 3413 SNMP Applications December 2002
INDEX { snmpNotifyFilterProfileName,
IMPLIED snmpNotifyFilterSubtree }
::= { snmpNotifyFilterTable 1 }
SnmpNotifyFilterEntry ::= SEQUENCE {
snmpNotifyFilterSubtree OBJECT IDENTIFIER,
snmpNotifyFilterMask OCTET STRING,
snmpNotifyFilterType INTEGER,
snmpNotifyFilterStorageType StorageType,
snmpNotifyFilterRowStatus RowStatus
}
snmpNotifyFilterSubtree OBJECT-TYPE
SYNTAX OBJECT IDENTIFIER
MAX-ACCESS not-accessible
STATUS current
DESCRIPTION
"The MIB subtree which, when combined with the corresponding
instance of snmpNotifyFilterMask, defines a family of
subtrees which are included in or excluded from the
filter profile."
::= { snmpNotifyFilterEntry 1 }
snmpNotifyFilterMask OBJECT-TYPE
SYNTAX OCTET STRING (SIZE(0..16))
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The bit mask which, in combination with the corresponding
instance of snmpNotifyFilterSubtree, defines a family of
subtrees which are included in or excluded from the
filter profile.
Each bit of this bit mask corresponds to a
sub-identifier of snmpNotifyFilterSubtree, with the
most significant bit of the i-th octet of this octet
string value (extended if necessary, see below)
corresponding to the (8*i - 7)-th sub-identifier, and
the least significant bit of the i-th octet of this
octet string corresponding to the (8*i)-th
sub-identifier, where i is in the range 1 through 16.
Each bit of this bit mask specifies whether or not
the corresponding sub-identifiers must match when
determining if an OBJECT IDENTIFIER matches this
family of filter subtrees; a '1' indicates that an
exact match must occur; a '0' indicates 'wild card',
i.e., any sub-identifier value matches.
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RFC 3413 SNMP Applications December 2002
Thus, the OBJECT IDENTIFIER X of an object instance
is contained in a family of filter subtrees if, for
each sub-identifier of the value of
snmpNotifyFilterSubtree, either:
the i-th bit of snmpNotifyFilterMask is 0, or
the i-th sub-identifier of X is equal to the i-th
sub-identifier of the value of
snmpNotifyFilterSubtree.
If the value of this bit mask is M bits long and
there are more than M sub-identifiers in the
corresponding instance of snmpNotifyFilterSubtree,
then the bit mask is extended with 1's to be the
required length.
Note that when the value of this object is the
zero-length string, this extension rule results in
a mask of all-1's being used (i.e., no 'wild card'),
and the family of filter subtrees is the one
subtree uniquely identified by the corresponding
instance of snmpNotifyFilterSubtree."
DEFVAL { ''H }
::= { snmpNotifyFilterEntry 2 }
snmpNotifyFilterType OBJECT-TYPE
SYNTAX INTEGER {
included(1),
excluded(2)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object indicates whether the family of filter subtrees
defined by this entry are included in or excluded from a
filter. A more detailed discussion of the use of this
object can be found in section 6. of [SNMP-APPL]."
DEFVAL { included }
::= { snmpNotifyFilterEntry 3 }
snmpNotifyFilterStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The storage type for this conceptual row.
Conceptual rows having the value 'permanent' need not
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RFC 3413 SNMP Applications December 2002
snmpProxyType OBJECT-TYPE
SYNTAX INTEGER {
read(1),
write(2),
trap(3),
inform(4)
}
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The type of message that may be forwarded using
the translation parameters defined by this entry."
::= { snmpProxyEntry 2 }
snmpProxyContextEngineID OBJECT-TYPE
SYNTAX SnmpEngineID
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The contextEngineID contained in messages that
may be forwarded using the translation parameters
defined by this entry."
::= { snmpProxyEntry 3 }
snmpProxyContextName OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The contextName contained in messages that may be
forwarded using the translation parameters defined
by this entry.
This object is optional, and if not supported, the
contextName contained in a message is ignored when
selecting an entry in the snmpProxyTable."
::= { snmpProxyEntry 4 }
snmpProxyTargetParamsIn OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object selects an entry in the snmpTargetParamsTable.
The selected entry is used to determine which row of the
snmpProxyTable to use for forwarding received messages."
::= { snmpProxyEntry 5 }
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RFC 3413 SNMP Applications December 2002
snmpProxySingleTargetOut OBJECT-TYPE
SYNTAX SnmpAdminString
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object selects a management target defined in the
snmpTargetAddrTable (in the SNMP-TARGET-MIB). The
selected target is defined by an entry in the
snmpTargetAddrTable whose index value (snmpTargetAddrName)
is equal to this object.
This object is only used when selection of a single
target is required (i.e. when forwarding an incoming
read or write request)."
::= { snmpProxyEntry 6 }
snmpProxyMultipleTargetOut OBJECT-TYPE
SYNTAX SnmpTagValue
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"This object selects a set of management targets defined
in the snmpTargetAddrTable (in the SNMP-TARGET-MIB).
This object is only used when selection of multiple
targets is required (i.e. when forwarding an incoming
notification)."
::= { snmpProxyEntry 7 }
snmpProxyStorageType OBJECT-TYPE
SYNTAX StorageType
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The storage type of this conceptual row.
Conceptual rows having the value 'permanent' need not
allow write-access to any columnar objects in the row."
DEFVAL { nonVolatile }
::= { snmpProxyEntry 8 }
snmpProxyRowStatus OBJECT-TYPE
SYNTAX RowStatus
MAX-ACCESS read-create
STATUS current
DESCRIPTION
"The status of this conceptual row.
To create a row in this table, a manager must
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RFC 3413 SNMP Applications December 2002
snmpProxySingleTargetOut,
snmpProxyMultipleTargetOut,
snmpProxyStorageType,
snmpProxyRowStatus
}
STATUS current
DESCRIPTION
"A collection of objects providing remote configuration of
management target translation parameters for use by
proxy forwarder applications."
::= { snmpProxyGroups 3 }
END
5. Identification of Management Targets in Notification Originators
This section describes the mechanisms used by a notification
originator application when using the MIB module described in this
document to determine the set of management targets to be used when
generating a notification.
A notification originator uses all active entries in the
snmpNotifyTable to find the management targets to be used for
generating notifications. Each active entry in this table selects
zero or more entries in the snmpTargetAddrTable. When a notification
is generated, it is sent to all of the targets specified by the
selected snmpTargetAddrTable entries (subject to the application of
access control and notification filtering).
Any entry in the snmpTargetAddrTable whose snmpTargetAddrTagList
object contains a tag value which is equal to a value of
snmpNotifyTag is selected by the snmpNotifyEntry which contains that
instance of snmpNotifyTag. Note that a particular
snmpTargetAddrEntry may be selected by multiple entries in the
snmpNotifyTable, resulting in multiple notifications being generated
using that snmpTargetAddrEntry (this allows, for example, both traps
and informs to be sent to the same target).
Each snmpTargetAddrEntry contains a pointer to the
snmpTargetParamsTable (snmpTargetAddrParams). This pointer selects a
set of SNMP parameters to be used for generating notifications. If
the selected entry in the snmpTargetParamsTable does not exist, the
management target is not used to generate notifications.
The decision as to whether a notification should contain an
Unconfirmed-Class or a Confirmed-Class PDU is determined by the value
of the snmpNotifyType object. If the value of this object is
trap(1), the notification should contain an Unconfirmed-Class PDU.
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RFC 3413 SNMP Applications December 2002
If the value of this object is inform(2), then the notification
should contain a Confirmed-Class PDU, and the timeout time and number
of retries for the notification are the value of
snmpTargetAddrTimeout and snmpTargetAddrRetryCount. Note that the
exception to these rules is when the snmpTargetParamsMPModel object
indicates an SNMP version which supports a different PDU version. In
this case, the notification may be sent using a different PDU type
([RFC2576] defines the PDU type in the case where the outgoing SNMP
version is SNMPv1).
6. Notification Filtering
This section describes the mechanisms used by a notification
originator application when using the MIB module described in this
document to filter generation of notifications.
A notification originator uses the snmpNotifyFilterTable to filter
notifications. A notification filter profile may be associated with
a particular entry in the snmpTargetParamsTable. The associated
filter profile is identified by an entry in the
snmpNotifyFilterProfileTable whose index is equal to the index of the
entry in the snmpTargetParamsTable. If no such entry exists in the
snmpNotifyFilterProfileTable, no filtering is performed for that
management target.
If such an entry does exist, the value of snmpNotifyFilterProfileName
of the entry is compared with the corresponding portion of the index
of all active entries in the snmpNotifyFilterTable. All such entries
for which this comparison results in an exact match are used for
filtering a notification generated using the associated
snmpTargetParamsEntry. If no such entries exist, no filtering is
performed, and a notification may be sent to the management target.
Otherwise, if matching entries do exist, a notification may be sent
if the NOTIFICATION-TYPE OBJECT IDENTIFIER of the notification (this
is the value of the element of the variable bindings whose name is
snmpTrapOID.0, i.e., the second variable binding) is specifically
included, and none of the object instances to be included in the
variable-bindings of the notification are specifically excluded by
the matching entries.
Each set of snmpNotifyFilterTable entries is divided into two
collections of filter subtrees: the included filter subtrees, and
the excluded filter subtrees. The snmpNotifyFilterType object
defines the collection to which each matching entry belongs.
To determine whether a particular notification name or object
instance is excluded by the set of matching entries, compare the
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RFC 3413 SNMP Applications December 2002
notification name's or object instance's OBJECT IDENTIFIER with each
of the matching entries. For a notification name, if none match,
then the notification name is considered excluded, and the
notification should not be sent to this management target. For an
object instance, if none match, the object instance is considered
included, and the notification may be sent to this management target.
If one or more match, then the notification name or object instance
is included or excluded, according to the value of
snmpNotifyFilterType in the entry whose value of
snmpNotifyFilterSubtree has the most sub-identifiers. If multiple
entries match and have the same number of sub-identifiers, then the
value of snmpNotifyFilterType, in the entry among those which match,
and whose instance is lexicographically the largest, determines the
inclusion or exclusion.
A notification name or object instance's OBJECT IDENTIFIER X matches
an entry in the snmpNotifyFilterTable when the number of sub-
identifiers in X is at least as many as in the value of
snmpNotifyFilterSubtree for the entry, and each sub-identifier in the
value of snmpNotifyFilterSubtree matches its corresponding sub-
identifier in X. Two sub-identifiers match either if the
corresponding bit of snmpNotifyFilterMask is zero (the 'wild card'
value), or if the two sub-identifiers are equal.
7. Management Target Translation in Proxy Forwarder Applications
This section describes the mechanisms used by a proxy forwarder
application when using the MIB module described in this document to
translate incoming management target information into outgoing
management target information for the purpose of forwarding messages.
There are actually two mechanisms a proxy forwarder may use, one for
forwarding request messages, and one for forwarding notification
messages.
7.1. Management Target Translation for Request Forwarding
When forwarding request messages, the proxy forwarder will select a
single entry in the snmpProxyTable. To select this entry, it will
perform the following comparisons:
- The snmpProxyType must be read(1) if the request is a Read-Class
PDU. The snmpProxyType must be write(2) if the request is a
Write-Class PDU.
- The contextEngineID must equal the snmpProxyContextEngineID object.
- If the snmpProxyContextName object is supported, it must equal the
contextName.
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RFC 3413 SNMP Applications December 2002
- The snmpProxyTargetParamsIn object identifies an entry in the
snmpTargetParamsTable. The messageProcessingModel, security model,
securityName, and securityLevel must match the values of
snmpTargetParamsMPModel, snmpTargetParamsSecurityModel,
snmpTargetParamsSecurityName, and snmpTargetParamsSecurityLevel of
the identified entry in the snmpTargetParamsTable.
There may be multiple entries in the snmpProxyTable for which these
comparisons succeed. The entry whose snmpProxyName has the
lexicographically smallest value and for which the comparisons
succeed will be selected by the proxy forwarder.
The outgoing management target information is identified by the value
of the snmpProxySingleTargetOut object of the selected entry. This
object identifies an entry in the snmpTargetAddrTable. The
identified entry in the snmpTargetAddrTable also contains a reference
to the snmpTargetParamsTable (snmpTargetAddrParams). If either the
identified entry in the snmpTargetAddrTable does not exist, or the
identified entry in the snmpTargetParamsTable does not exist, then
this snmpProxyEntry does not identify valid forwarding information,
and the proxy forwarder should attempt to identify another row.
If there is no entry in the snmpProxyTable for which all of the
conditions above may be met, then there is no appropriate forwarding
information, and the proxy forwarder should take appropriate actions.
Otherwise, The snmpTargetAddrTDomain, snmpTargetAddrTAddress,
snmpTargetAddrTimeout, and snmpTargetRetryCount of the identified
snmpTargetAddrEntry, and the snmpTargetParamsMPModel,
snmpTargetParamsSecurityModel, snmpTargetParamsSecurityName, and
snmpTargetParamsSecurityLevel of the identified snmpTargetParamsEntry
are used as the destination management target.
7.2. Management Target Translation for Notification Forwarding
When forwarding notification messages, the proxy forwarder will
select multiple entries in the snmpProxyTable. To select these
entries, it will perform the following comparisons:
- The snmpProxyType must be trap(3) if the notification is an
Unconfirmed-Class PDU. The snmpProxyType must be inform(4) if the
request is a Confirmed-Class PDU.
- The contextEngineID must equal the snmpProxyContextEngineID object.
- If the snmpProxyContextName object is supported, it must equal the
contextName.
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RFC 3413 SNMP Applications December 2002
- The snmpProxyTargetParamsIn object identifies an entry in the
snmpTargetParamsTable. The messageProcessingModel, security model,
securityName, and securityLevel must match the values of
snmpTargetParamsMPModel, snmpTargetParamsSecurityModel,
snmpTargetParamsSecurityName, and snmpTargetParamsSecurityLevel of
the identified entry in the snmpTargetParamsTable.
All entries for which these conditions are met are selected. The
snmpProxyMultipleTargetOut object of each such entry is used to
select a set of entries in the snmpTargetAddrTable. Any
snmpTargetAddrEntry whose snmpTargetAddrTagList object contains a tag
value equal to the value of snmpProxyMultipleTargetOut, and whose
snmpTargetAddrParams object references an existing entry in the
snmpTargetParamsTable, is selected as a destination for the forwarded
notification.
8. Intellectual Property
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
9. Acknowledgments
This document is the result of the efforts of the SNMPv3 Working
Group. Some special thanks are in order to the following SNMPv3 WG
members:
Harald Tveit Alvestrand (Maxware)
Dave Battle (SNMP Research, Inc.)
Alan Beard (Disney Worldwide Services)
Paul Berrevoets (SWI Systemware/Halcyon Inc.)
Levi, et. al. Standards Track [Page 67]

RFC 3413 SNMP Applications December 2002
As recommended by the Advisory Team and the SNMPv3 Working Group
Charter, the design incorporates as much as practical from previous
RFCs and drafts. As a result, special thanks are due to the authors
of previous designs known as SNMPv2u and SNMPv2*:
Jeff Case (SNMP Research, Inc.)
David Harrington (Enterasys Networks)
David Levi (Nortel Networks)
Keith McCloghrie (Cisco Systems)
Brian O'Keefe (Hewlett Packard)
Marshall T. Rose (Dover Beach Consulting)
Jon Saperia (BGS Systems Inc.)
Steve Waldbusser (International Network Services)
Glenn W. Waters (Bell-Northern Research Ltd.)
10. Security Considerations
The SNMP applications described in this document typically have
direct access to MIB instrumentation. Thus, it is very important
that these applications be strict in their application of access
control as described in this document.
In addition, there may be some types of notification generator
applications which, rather than accessing MIB instrumentation using
access control, will obtain MIB information through other means (such
as from a command line). The implementors and users of such
applications must be responsible for not divulging MIB information
that normally would be inaccessible due to access control.
Finally, the MIBs described in this document contain potentially
sensitive information. A security administrator may wish to limit
access to these MIBs.
11. References11.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2578] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M. and S. Waldbusser, "Structure of Management
Information Version 2 (SMIv2)", STD 58, RFC 2578, April
1999.
[RFC2579] McCloghrie, K., Perkins, D., Schoenwaelder, J., Case, J.,
Rose, M. and S. Waldbusser, "Textual Conventions for
SMIv2", STD 58, RFC 2579, April 1999.
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RFC 3413 SNMP Applications December 2002
Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Levi, et. al. Standards Track [Page 74]